Even slightly higher levels took their toll, researchers note
Many folks in their 30s and 40s chow down on burgers, fried chicken and other fatty foods without fear, figuring they have years before they need to worry about their cholesterol levels.
But new research reveals that long-term exposure to even slightly higher cholesterol levels can damage a person's future heart health.
People at age 55 who've lived with 11 to 20 years of high cholesterol showed double the risk of heart disease compared to people that age with only one to 10 years of high cholesterol, and quadruple the risk of people who had low cholesterol levels, researchers report online Jan. 26 in the journal Circulation.
"The duration of time a person has high cholesterol increases a person's risk of heart disease above and beyond the risk posed by their current cholesterol level," said study author Dr. Ann Marie Navar-Boggan, a cardiology fellow at the Duke Clinical Research Institute in Durham, N.C. "Adults with the highest duration of exposure to high cholesterol had a fourfold increased risk of heart disease, compared with adults who did not have high cholesterol."
Navar-Boggan and her colleagues concluded that for every 10 years a person has borderline-elevated cholesterol between the ages of 35 and 55, their risk of heart disease increases by nearly 40 percent.
"In our 30s and 40s, we are laying the foundation for the future of our heart health," she said.
For this study, which was partly funded by the U.S. Agency for Healthcare Research and Quality, researchers relied on data from the Framingham Heart Study, one of the largest ongoing research projects focused on heart health. Since 1948, families in the town of Framingham, Mass., have allowed researchers to track their health.
The researchers took 1,478 adults from the study who had not developed heart disease by age 55, and then calculated the length of time each person had experienced high cholesterol by that age.
They defined high cholesterol very conservatively in this study, pegging it at about 130 mg/dL of "bad" LDL cholesterol, a level which the U.S. National Institutes of Health considers the lowest end of "borderline high" cholesterol.
Researchers then followed these adults for up to 20 years past age 55 to see how their exposure to high cholesterol affected their risk of heart disease.
The results showed that a person's long-term "dose" of high cholesterol appears to directly affect their future risk of heart disease:
- Participants with 11 to 20 years of high cholesterol had a 16.5 percent overall risk of heart disease.
- Those with one to 10 years of cholesterol exposure had 8.1 percent risk.
- Those who did not have high cholesterol at the start of the study had only a 4.4 percent risk for heart disease.
Navar-Boggan compared extended exposure to high cholesterol to the concept of "pack years" in smoking, where doctors assess a person's health risk by determining how heavily they smoked and for how long.
"We should really be thinking about cholesterol the same way," she said. "What are your cholesterol years?"
Dr. Robert Eckel, past president of the American Heart Association, said if these new results are confirmed in future studies, it could influence guidelines on the use of cholesterol-lowering statin drugs.
Under current guidelines, only one in six adults in this study with extended exposure to high cholesterol would have been recommended for statin therapy at age 40, and one in three would have been at age 50, the researchers noted.
"Only 15 percent would have made the criteria for statin treatment, and that suggests that the guideline was inadequate in addressing patients in this area of risk," said Eckel, a professor of medicine at the University of Colorado Denver, Anschutz Medical Campus. "The study identifies people who should have been treated, where the guidelines say they don't meet criteria for treatment."
But Navar-Boggan said she's cautious about making the leap to recommending statins for people in their 30s and early 40s.
People in their 30s definitely should be screened at least once for high cholesterol, she said. Those that age who have high cholesterol should first try to bring their levels down through exercise and a heart-healthy diet.
"We have to be cautious in interpreting this to say that people in their 30s should be taking a statin. That potentially commits them to taking a medication over decades of life," she said, noting that little is known about the long-term health effects of statin use.